The present invention is related to gas treatment of products, specifically food and similar products, using gas jets which impinge upon the products for e.g. cooling, heating or drying them.
Devices for cooling or heating food products are known from e.g. U.S. Pat. No. 4,679,542 to Donald P. Smith et al. These devices comprise a housing in which a high-pressure gas plenum communicates with upper and lower ducts defining a treatment area therebetween and having a plurality of nozzles for ejecting gas jets vertically into the treatment area. The food products to be treated are supported by a conveyor belt that transports them through the treatment area.
The design of these known devices is quite complex, resulting in difficulties in meeting the high hygienic requirements of the food industry. Also, the maintenance of the prior art devices is time-consuming, and the intervals between successive shutdowns are short.
Another apparatus for cooling, heating or drying of products is known from U.S. Pat. No. 5,408,921 to Per-Oskar Persson et al. This apparatus comprises a housing and a conveyor belt for transporting the products through the housing along a path from an inlet opening to an outlet opening in the housing. A tunnel encloses the conveyor belt at least along a part of the path from the inlet opening to the outlet opening. Cold air is circulated by fan means through perforations in the tunnel walls opposite to the products carried on the conveyor belt such that air jets impinge upon the surface of the products, and further out of the tunnel to air conditioning means for conditioning the air and then back to the outside of the tunnel.
This prior art apparatus substantially eliminates or at least reduces the above-noted problems of the devices known from e.g. U.S. Pat. No. 4,679,542 to Donald P. Smith et al.
However, the known devices and apparatus are relatively bulky.
Therefore, one object of the present invention is to provide a compact apparatus for gas treatment of products.
Another object of the present invention is to provide such an apparatus which meets the high hygienic requirements of the food industry.
According to the present invention these objects are attained by an apparatus for gas treatment of products which a housing having top, bottom and side-walls; a conveyor belt for transporting the products along a first path in the housing; a tunnel having perforated walls and enclosing the conveyor belt along the first path; gas circulation means communicating with the tunnel via the perforated walls for circulating gas into the tunnel in the form of gas jets impinging upon the products carried by the conveyor belt, and out of the tunnel in a return channel back to the gas circulation means, and gas conditioning means positioned in the return channel for conditioning the gas circulated by the gas circulation means. Further, walls connecting with the perforated walls of the tunnel and having an opening towards the gas circulation means, form a high-pressure chamber substantially above the tunnel and spaced from the walls of the housing. Finally, at least one substantially vertical part of the connecting walls of the high-pressure chamber is removable so as to provide access to the inside of the pressure chamber.
By this configuration, a compact design is obtained which also provides easy access to all parts of the apparatus, which is a condition for fulfilling the high hygienic requirements of the food industry.
Preferably, at least one substantially vertical part of the connecting walls of the high-pressure chamber is slidable or articulated for providing an access opening into the high-pressure chamber.
In a preferred embodiment, the vertical parts of the connecting walls on both sides of and all along the tunnel in the high-pressure chamber are removable.
Further, the conveyor belt is preferably foraminous, the top wall of the tunnel being perforated substantially over its whole area, and the bottom wall of the tunnel having perforated sections extending transversely of the first path, such that the gas jets may impinge upon both the top side and the bottom side of the products on the, conveyor belt.
In a most preferred embodiment, at least one of the side walls of the housing along the high-pressure chamber is removable so as to widen the space between said at least one wall and the high-pressure chamber. This results in a very compact configuration, still fulfilling high demands on access to all parts of the apparatus.